Traditionally, speakers who make audio-visual presentations to groups of people have used one of two common pieces of projection equipment--a slide projector, typically employing 35 mm photographic slides, or an overhead projector, which utilizes overhead transparencies. Each of these types of projectors has advantages and disadvantages. Slides used in slide projectors can be prepared to look very professional, but they require significant advance preparation (which can be both time consuming and expensive), and they typically must be pre-loaded into a slide tray, making it difficult to easily or quickly change the order of the presentation, particularly during the presentation. Overhead transparencies, on the other hand, can be created more easily than photographic slides, and can be rearranged easily just before or even during a presentation. Unlike a slides in a slide projector, however, overhead transparencies cannot be remotely changed by the speaker. Rather, the speaker (or an assistant) must physically place each transparency in the proper position on the projector. This process often is distracting to both the speaker and the audience, and the distraction can be exacerbated by improper alignment of the transparency on the projector, a very common difficulty. Also, without a careful organizational system, transparencies can easily get out of order from one presentation to the next.
Advances in personal computing and desktop publishing have enabled even the average computer user to easily and economically produce professional quality reports, charts, graphs, and other visual aids. Use of such visual aids in presentations, however, requires conversion of the computer generated image to some other medium, such as a slide or transparency, that is capable of being projected by conventional projection equipment. Though it is possible to create overhead transparencies even in color, the process is not always convenient or inexpensive.
Color video projectors have become available in recent years. Such projectors have most commonly been used as large screen TV projectors, and currently are popular both in "home theaters" (i.e., large screen systems installed in one's home) and in conference room settings for the display of video tapes. With the proper interfaces, it is possible to display the video signal from a computer on a large screen TV through such color video projectors. Such projectors are both expensive and bulky, however, and, therefore, are often mounted in a relatively permanent installation. As such, they are not typically suitable for portable use in the way that an overhead or slide projector may be used.
Advancements in LCD panel technology have opened new avenues for projection techniques. In particular, several companies (including the assignee of the present application) have introduced computer-driven LCD panels which can be placed on a conventional overhead projector. The LCD panel displays the video output of the computer, which is then projected on a screen. Since laptop computers typically use an LCD panel as the computer monitor, some companies have even introduced laptops which allow the LCD panel to function both as a traditional screen and as an overhead projection panel which can be placed on an overhead projector, as described above. Such LCD panels, though portable, nevertheless require the use of separate, conventional overhead projectors (which typically are themselves somewhat bulky). A presenter must therefore nevertheless rely on the availability of an overhead projector at the site of the presentation (or else carry not only the notebook computer containing the presentation graphics but also the portable LCD panel and a "portable" overhead projector.
To solve this inconvenience, some "desktop" projectors have been manufactured with built-in LCD panels, alleviating the need for a separate overhead projector. Such desktop projectors, however, are nevertheless relatively bulky and would not be considered to be truly "portable". For example, one such projector sold by the assignee of the present application under the model name "P170" is about 6.75" tall with a footprint of 12".times.15", weighing 12.3 lbs. Though smaller than many overhead projectors, it is significantly larger than, e.g., a notebook computer. In particular, in order to house an LCD panel of suitable size, this projector is of necessity more than twice as tall (i.e., thick) as a typical notebook computer. Accordingly, such projectors are not as easily or conveniently transported as are, e.g., notebook computers.